(1) Field of the Invention
This invention relates to u-joint, flexible drill pipes and equipment used to bore horizontal drain holes in oil, gas, or water formations.
(2) Description of Related Art
The way flexible drill pipes are used to drill horizontal holes from a vertical well hole is to drill a curved hole from the vertical to the horizontal and then proceed to drill a straight horizontal hole out into the formation.
The problem with standard flexible drill pipes in drilling horizontal drain holes in oil, gas or water formations is the flexibility required to operate around a curved hole from the vertical to the horizontal becomes a great problem in drilling a straight horizontal hole.
This invention provides a flexible/rigid drilling assembly, which can transition around the curved hole and converts to rigid assembly providing a rigid section right behind the drill bit. This rigid section will reduce the flexibility right behind the drill bit and provide more stability in drilling a straight horizontal hole. This capability could significantly increase the distance a horizontal hole can be drilled from a vertical well and increased the production from oil, gas or water wells.